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A user-space file system for on-demand legacy desktop software

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science china(information sciences) 2011年第6期54卷 1142-1150页

作者： ZHANG YouHui 1,2 , SU GeLin 1,2 & ZHENG WeiMin 1,2 1 Department of Computer science and technology, tsinghua University, beijing 100084, china 2 tsinghua national laboratory for information science and technology, tsinghua University, beijing 100084, china 1. Department of Computer science and technology Tsinghua University Beijing 100084 China2. Tsinghua National Laboratory for Information Science and Technology Tsinghua University Beijing 100084 China

Some user-level virtualization technologies have been used to convert legacy software (like the existing Windows desktop applications) into the on-demand software without any modification. To give the client a friendly and compatible method to access on-demand legacy software across the Internet, this paper presents a clientend file system for this usage case. It is a Windows user-space file system based on the cloud storage (where the on-demand software is stored), which converts the local file system accesses into remote visits. Quite a few optimizations are adopted and adjusted to suit the file-access-pattern of on-demand software, including the local cache, metadata/data/software prefetch and content-addressable storage (CAS), to decrease the number of remote visits and/or to overlap IO (input/output) operations with software execution. Detailed access-pattern analyses are also presented. This file system has been implemented and tests show that it is practical for much daily-used software-a local cache of limited size can provide up to 80% hit ratio and the corresponding overhead of running-time is about 37%. Owing to this method, on any compatible and networked computer, a user can use his/her personalized software conveniently although it does not exist on the local host.

关键词： on-demand software software as a service user-space file system cloud storage

Real-time reliability prediction for dynamic systems with both deteriorating and unreliable components

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science in china(Series F) 2009年第11期52卷 2234-2246页

作者： XU ZhengGuo1,2, JI YinDong2,3 & ZHOU DongHua1,2? 1 Department of Automation, tsinghua University, beijing 100084, china 2 tsinghua national laboratory for information science and technology, tsinghua University, beijing 100084, china 3 Research Institute of information technology (RIIT), tsinghua University, beijing 100084, china Department of Automation Tsinghua University Beijing 100084 China tsinghua national laboratory for information science and technology Tsinghua University Beijing 100084 China Research Institute of information technology (RIIT) Tsinghua University Beijing 100084 China

As an important technology for predictive maintenance, failure prognosis has attracted more and more attentions in recent years. Real-time reliability prediction is one effective solution to failure prognosis. Considering a dynamic system that is composed of normal, deteriorating and unreliable components, this paper proposes an integrated approach to perform real-time reliability prediction for such a class of systems. For a deteriorating component, the degradation is modeled by a time-varying fault process which is a linear or approximately linear function of time. The behavior of an unreliable component is described by a random variable which has two possible values corresponding to the operating and malfunction conditions of this component. The whole proposed approach contains three algorithms. A modified interacting multiple model particle filter is adopted to estimate the dynamic system＇s state variables and the unmeasurable time-varying fault. An exponential smoothing algorithm named the Holt＇s method is used to predict the fault process. In the end, the system＇s reliability is predicted in real time by use of the Monte Carlo strategy. The proposed approach can effectively predict the impending failure of a dynamic system, which is verified by computer simulations based on a three-vessel water tank system.

关键词： reliability failure prognostics dynamic systems fault prediction particle filtering interacting multiple model exponential smoothing,predictive maintenance

Eavesdropping in a quantum secret sharing protocol based on Grover algorithm and its solution

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science china(Physics,Mechanics & Astronomy) 2010年第3期53卷 491-495页

作者： HAO Liang1, LI JunLin1 & LONG GuiLu1,2 1Key laboratory for Atomic and Molecular Nanosciences and Department of Physics, tsinghua University, beijing 100084, china 2tsinghua national laboratory for information science and technology, beijing 100084, china 1. Key laboratory for Atomic and Molecular Nanosciences and Department of Physics Tsinghua University Beijing 100084 China2. Tsinghua National Laboratory for Information Science and Technology Beijing 100084 China

A detailed analysis has showed that the quantum secret sharing protocol based on the Grover algorithm (Phys Rev A, 2003, 68: 022306) is insecure. A dishonest receiver may obtain the full information without being detected. A quantum secret-sharing protocol is presents here, which mends the security loophole of the original secret-sharing protocol, and doubles the information capacity.

关键词： quantum secret sharing Grover algorithm quantum cryptography quantum search algorithm

Suppression of Phase and Amplitude Damping Decoherence in a Three-Level Atom in A-Configuration Using Bang-Bang Controls

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Communications in Theoretical Physics 2007年第7期48卷 71-74页

作者： WANG Yan-Hui LIU Xiao-Shu LONG Gui-Lu1 Key laboratory for Atomic and Molecular Nanosciences and Department of Physics,tsinghua University,beijing 100084,china2 tsinghua national laboratory for information science and technology,tsinghua University,beijing 100084,china Key laboratory for Atomic and Molecular Nanosciences and Department of Physics Tsinghua University Beijing 100084 China tsinghua national laboratory for information science and technology Tsinghua University Beijing 100084 China

In this paper,we present decoupling bang-bang operations for the suppression of general decoherence,bothamplitude and phase damping,in a three-level system in *** give a program to design a sequence ofperiodic twinbor... 详细信息

关键词： bang-bang operation general decoherence three-level system

Self-healing routing: failure,modeling and analysis

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science china(information sciences) 2011年第3期54卷 609-622页

作者： XU MingWei 1,2 , LI Qi 1,2 , YANG Yuan 1,2 , HOU MeiJia 1,2 & PAN LingTao 1,2 1 Department of Computer science, tsinghua University, beijing 100084, china 2 tsinghua national laboratory for information science and technology (TNList), beijing 100084, china 1. Department of Computer science Tsinghua University Beijing 100084 China2. Tsinghua National Laboratory for Information Science and Technology (TNList) Beijing 100084 China

Network failures occur frequently, and self-healing ability of existing routing protocols cannot guarantee fast route convergence under these failures without impacting packet forwarding. During routing convergence, network routes may be incorrect and even routing black holes and loops occur, which will result in extensive packet loss and thus influence network performance. To solve this problem, several improved routing solutions have been proposed. In this paper, we propose the concept and model of self-healing routing and analyze the key problems in current intra-domain and inter-domain self-healing routing protocols after briefly reviewing the characteristics of network failures. We classify the different self-healing solutions into two categories based on their design principles: routing restoration and routing protection, and systematically analyze these different typical solutions. Finally, we discuss several key issues in self-healing routing and propose a hybrid protection and restoration based routing scheme.

关键词： failure intra-domain routing inter-domain routing self-healing routing

Arbitrarily long distance quantum communication using inspection and power insertion

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Chinese science Bulletin 2009年第1期54卷 158-162页

作者： WANG WanYing1,2,WANG Chuan1,2,ZHANG GuangYu1,3 & LONG GuiLu1,2 1 Department of Physics,tsinghua University,beijing 100084,china 2 tsinghua national laboratory for information science and technology,tsinghua University,beijing 100084,china 3 College of Applied science,Harbin University of science and technology,Harbin 150080,china Department of Physics Tsinghua University Beijing 100084 China tsinghua national laboratory for information science and technology Tsinghua University Beijing 100084 China College of Applied science Harbin University of Science and Technology Beijing 100084 China

The biggest obstacle for long distance quantum communication is the channel loss and the channel noise on photons. In this paper,a method to solve this problem was analyzed using inspection and power insertion (IPI). It is proved that quantum communication may be established over arbitrarily long distance using this technology. The amount of resources required is a polynomial function of the dis-tance. IPI is proposed as a general technique to prolong quantum secure direct communication where secret messages are transmitted directly over a quantum channel.

关键词：长距离量子通信量子安全通信量子密匙分布噪声

Development of silicon-based microelectrode array

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science china(Technological sciences) 2009年第8期52卷 2391-2395页

作者： LIN JianHui1,2,3, WU XiaoMing1,2,3,4, HUANG PengSheng1,2, FENG Lei5, REN TianLing1,2 & LIU LiTian1,2 1 Institute of Microelectronics, tsinghua University, beijing 100084, china 2 tsinghua national laboratory for information science and technology, beijing 100084, china 3 Yangtze Delta Region Institute of tsinghua University, Jiaxing 314050, china 4 State Key laboratory of Transducer technology, Chinese Academy of sciences, Shanghai 200050 china 5 Department of Biomedical Engineering, tsinghua University, beijing 100084, china 1. Institute of Microelectronics Tsinghua University Beijing 100084 China 2. tsinghua national laboratory for information science and technology Beijing 100084 China 3. Yangtze Delta Region Institute of tsinghua University Jiaxing 314050 China 4. State Key laboratory of Transducer technology Chinese Academy of Sciences Shanghai 200050 China 5. Department of Biomedical Engineering Tsinghua University Beijing 100084 China

This paper introduces in details a kind of silicon-based microelectrode array. MEMS (micro-electromechanical system) technology is used in the fabrication of the microelectrode array, which is designed to perform signal recording and electrical stimulation for nerves in neural engineering. A simple fabrication process is developed. An improved model of microelectrodes is brought forward and successfully validated by the excellent match between circuit simulations and electrical measurements, including both magnitude and phase of microelectrode impedance. Compared with the simple one that is usually used, the improved model is believed to be an advance and more accurate. This modeling helps to improve the design of microelectrodes and understand the behavior of interface between electrode and cell. Furthermore, the microelectrode is proved to be a feasible tool for researches in neural engineering by successfully recording neural activities of sciatic nerve of a bullfrog.

关键词： microelectrode array MEMS neural engineering

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P2P技术分析与流量管理研究

计算机科学 2010年第4期37卷 1-6,10页

作者：王春刚王会杨家海清华大学计算机科学与技术系北京100084 清华大学信息网络工程研究中心北京100084 清华信息科学与技术国家实验室北京100084

随着P2P应用的日益流行,P2P流量消耗了网络的大量带宽,已经影响到了互联网传统业务的服务质量。为解决这一问题,网络运营者和研究人员在P2P流量的管理技术上进行了大量的探索研发工作,主要有P2P流量阻塞、缓存和本地化疏导等技术。首先... 详细信息

随着P2P应用的日益流行,P2P流量消耗了网络的大量带宽,已经影响到了互联网传统业务的服务质量。为解决这一问题,网络运营者和研究人员在P2P流量的管理技术上进行了大量的探索研发工作,主要有P2P流量阻塞、缓存和本地化疏导等技术。首先对P2P技术做了简单概述,然后分析了影响P2P流量分布的重要技术因素,之后综述了最新的P2P流量管理技术,最后做了总结。

关键词： P2P 流量分布节点选择

A Multi-objective Control for Urban Intersections Based on 3E Criteria

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A Multi-objective Control for Urban Intersections Based on 3...